instance and item now use dynamic dispatch

src/core/instance/store.rs

@@ -15,14 +15,14 @@ pub trait Store {
     // is implemented, so that there can be a multithreaded implementation
     //fn get(self, id: MizeId) -> MizeResult<Item<Self>> where Self: Sized;
 
-    fn set<T: Into<ItemData>>(&self, id: MizeId, data: T) -> MizeResult<()>;
+    fn set(&self, id: MizeId, data: ItemData) -> MizeResult<()>;
 
     // in the future should implement transactions, ....
 
     // funcs to do with links, backlinks
-    fn get_links(&self, item: Item<Self>) -> MizeResult<Vec<MizeId>> where Self: Sized;
+    fn get_links(&self, item: Item) -> MizeResult<Vec<MizeId>>;
 
-    fn get_backlinks(&self, item: Item<Self>) -> MizeResult<Vec<MizeId>> where Self: Sized;
+    fn get_backlinks(&self, item: Item) -> MizeResult<Vec<MizeId>>;
 
     fn new_id(&self) -> MizeResult<String>;
 
@@ -30,6 +30,40 @@ pub trait Store {
 
     fn get_value_data_full(&self, id: MizeId) -> MizeResult<ItemData>;
 
-    fn id_iter(&self) -> MizeResult<impl Iterator<Item=String> + '_>;
+    fn id_iter(&self) -> MizeResult<IdIter>;
+
+    fn next_id(&self, prev_id: &str) -> MizeResult<Option<String>>;
+
+    fn first_id(&self) -> MizeResult<String>;
+}
+
+pub struct IdIter {
+    cur_id: String,
+    store: Box<dyn Store>,
+}
+
+impl IdIter {
+    pub fn new(store: Box<dyn Store>) -> MizeResult<IdIter> {
+        Ok(IdIter { cur_id: store.first_id()?, store })
+    }
+}
+
+impl Iterator for IdIter {
+    type Item = MizeResult<String>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.store.next_id(&self.cur_id) {
+            Err(err) => {
+                Some(Err(err))
+            },
+            Ok(Some(new_id)) => {
+                self.cur_id = new_id.clone();
+                Some(Ok(new_id))
+            },
+            Ok(None) => {
+                None
+            },
+        }
+    }
 }